As well known to those skilled in the art, the process for testing semiconductor devices is performed after the fabrication of wafers to measure the quality of semiconductor chips of each wafer. During the chip testing process, it is possible to pick out bad quality chips from high quality chips prior to returning repairable chips to the fabrication process to recycle them. Such bad quality chips are thus completely prevented from being further processed. This testing process effectively reduces the packaging and testing cost while producing semiconductor devices.
FIG. 1A shows a typical test system used in the process for testing the semiconductor devices.
FIG. 1B is an overhead view of the wafer in FIG. 1A.
As shown in FIG. 1A, the system 1 comprises a tester 10, a prober 12, and an executing board 14. The tester 10 outputs an electric signal to a semiconductor device and reads response data to determine whether the semiconductor device has normal characteristics. The prober 12 is for loading a wafer 18 on a die in a way such that a probe card 16 is aligned with and brought into contact with the wafer 18. It is possible for the above prober 12 to selectively unload the wafer 18 from the die or to move the wafer 18 within dimensions of the die under the control of the tester 10. The executing board 14 transmits the signal from the tester 10 to the prober 12.
FIG. 1B is an overhead view of the wafer 18 in FIG. 1A. As shown in FIG. 1B, the wafer 18 includes a semiconductor device 17 having terminals 19. Although only one semiconductor device 17 is shown, it is understood that there may be more than one on the wafer 18.
During the operation of the above testing system 1, the signal output from the tester 10 is transmitted to the test tip 15 of the probe card 16 through the executing board 14. The test tip is thereafter brought into contact with the terminals 19 of each of the semiconductor devices 17 of the wafer 18, thus allowing an electric signal to flow into the circuit of the semiconductor device.
Such probe cards are typically classified into two types: blade type cards and epoxy type cards in accordance with the types of test tips. The blade type cards individually have a blade type test tip, while the epoxy type cards individually have an epoxy type test tip. The blade type probe cards are generally used for testing semiconductor devices having sixty or fewer pins.
The process for testing semiconductor devices comprises the steps of mounting a test tip on the probe card 16, applying an electric signal to each semiconductor chip of a wafer 18 through the test tip, and determining a production yield of the semiconductor devices by checking the electric characteristics of each device. The test tip thus comes into repeated contact with the semiconductor chips and this reduces the expected life span of such a test tip. This also forces the owner of the system to frequently change the test tip with a new one and reduces productivity of semiconductor devices.
Due to such repeated contact of the test tip with the semiconductor chips, the metal test tip can become scratched and/or frictionally abraded so that the contact area of the tip per unit is enlarged, which increases the contact resistance of the test tip. In such a case, the test system may fail to exactly measure the electric characteristics of the semiconductor chips, thus sometimes measuring normal chips as abnormal chips thereby reducing the manufacturing yield of the chips. In particular, when wafers for linear integrated circuit devices are tested by the typical test system, it is necessary to use an application circuit, active and passive elements along with the probe card. In such a case, it is almost impossible to automatically measure the characteristics, such as resistance, electrostatic capacity, and flatness, of the test tip so that the test tip has to be checked by the naked eye of a user. In addition, the repeated changing of test tips may force the solder mark of the probe card to be unexpectedly removed from the probe card due to the high temperature soldering heat. In such a case, the probe card has to be changed with a new one, which forces the owner of the system to newly produce a probe card, newly register data in the new card, and check the manufacturing yield.